To experience the future, the past and the terror of commuting by bike in San Francisco, pedal north up Polk Street from Market. Polk is undergoing a reconfiguration and repaving, so it's a good test case for what may happen in the city.

Polk begins with a green, silky-smooth separated bike freeway, funnels into a thin lane marked by a white line and then morphs into the kind of narrow, scary, oh-my-God-I-hope-no-driver-opens-his-car-door obstacle course that used to be the norm in the city.

Leah Shahum, executive director of the San Francisco Bicycle Coalition, and I rode up Polk last week on a typical weekday afternoon. Except for the obvious - she had a nicer bike - we could have been any regular commuters. We didn't really have any near misses, but we did slalom around potholes, warn each other about erratic drivers and engage in a few of those one-way seriously-what-in-the-name-of-God-are-you-doing conversations with drivers blocking bike lanes.

"I would say the first three blocks are the gold standard, an A+," Shahum said. "Then we go to existing bike lanes, which is way better than nothing. I'd give that a C+. And then from Post to Union there's no lane, no separation. The No. 1 way people get hurt riding in the city is getting 'doored.' I'd give that a D."

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"Polk Street sets a tone for what can happen in a mixed-use street," says Shahum. "It is important because it sends a message."

The message? Now that the bikes are here, what are we going to do with them? It seems pretty obvious that the city needs to identify some north-south/east-west cycling routes that are safe and simple to use. That's the concept. The reality is a little more difficult.

As Shahum says, the usual discussion goes like this:

"Are you in favor of connected bike routes in the city?"

"Of course."

"Would you want one in front of your house?"

"Of course not."

Well somebody is going to be unhappy, because this is going to happen. The simple numbers make it inevitable.

A San Francisco Municipal Transit Agency survey found that since 2006 cycling in the city is up 96 percent. Those of us who work near Market Street agree with data that shows some 6,000 bike trips per day on weekdays. And, in one day in 2013, at 51 intersections, the SFMTA counted 23,225 bike trips in an afternoon between 4:30 and 6:30.

So clearly more must be done to create arterial routes in the city, right? In theory, sure. But let's go back to Polk and tap into what happened when the Polk Streetscape project was begun.

"There have been public meetings," Shahum says. "Lots of yelling. Lots of energy."

The problem - or the advantage, depending on who you're talking to - is that Polk is the incline of choice for bike riders attempting to go from Market Street toward the Marina. It is not as steep as nearby streets and nowhere near as busy. The streets parallel to Polk are virtual freeways in some spots, which is why, on average, bike traffic is up 34 percent there since 2011.

"So what if we take away one parking lane?" asks Shahum.

Cue the howls of protest. Merchants don't want to see parking taken away, which makes a certain amount of sense. Shahum says her group has a plan.

"You could recoup the parking by taking away a lane on a side street and making it head-in parking," she said.

Improvements ahead

OK, great. So now we have changes on two streets instead of one. And how's that going over?

"We keep raising the idea with the city," Shahum said. "But they're not looking at it."

Better keep looking. As Shahum says, several streets are already on tap for bike improvements. Second Street is already funded and Masonic is already improved.

In the near future it may be that San Francisco will become much more bike friendly.